1. Field of the Invention
The present invention relates to an apparatus and method of self-optimization for a forbidden neighbor cell list.
2. Description of the Related Art
The optimization of the neighbor cell list (NCL) is one of the most important optimization processes that operators have to deal with in order to provide continuous mobility and good quality service. Typically, the neighbor cell list is defined manually by operators based on simulations and field trials. The target is to include potential candidate cells for mobility in idle mode and dedicated mode.
In global system for mobile communication (GSM) enhanced data rates for global evolution (EDGE) radio access network (GERAN) and universal mobile telecommunications system (UMTS) terrestrial radio access network (UTRAN), an operator has the control of a neighbor cell list. Thus, if a target cell is not performing well, the operator can take this neighbor cell out of the neighbor cell list. By doing so, a network element, such as a user equipment (UE), will not report the bad neighbor cell anymore. In addition, filtering mechanisms can be applied so that only the neighbor cells with the strongest radio conditions are reported by the UE. However, filtering cannot address all of the potential problems related to handover performance.
In some second generation (2G) and third generation (3G) inter-working networks, the neighbor cell list is optimized (or generated) in order to provide good service for the normal user/customer. It may be part of the network policy to have some users (e.g., roaming) using different rules than the general. In a very specific example, the operator might want to limit some users' access to certain cells or other radio access network (RAN).
In 3GPP RAN2, some ongoing discussions contemplate whether NCL is to be used or not. In addition, due to the time consuming process in updating the neighbor cell list, some self-optimization procedures has been proposed in GERAN and UTRAN and in perhaps in other systems. Forbidden neighbor cell list (FNCL) or also known as the “black list” is one feature for handling mobility in Evolved UTRAN (E-UTRAN). The black or forbidden list contains a list of neighbor cells that UE should not take into considerations for cell reselection or handover purposes. However, the state of the art does not provide any good solutions for mechanisms how to self-optimize (define the list of neighbors) in the FNCL.